Grinding block



F. A. VAVRIN GRINDING BLOCK Jan. 23, 1951 Filed Aug. 2, 1948 NNW v A ATTORNEYS l; A further important object of the Patented Jan. 23, 1951UNITED STATES PATENT OFFICE 2,539,289 GRINDING BLOCK Frank AgVavrin,Racine, Wis. Application August 2, 1948, Serial No. 42,089

1 Claim. 1

This invention appertains to grindin blocks, and more particularly to anovel device for hold-- ing; thread cuttin tools during the sharpeningor shapening of the various faces and edges thereof for the correctforming of a certain desired thread on a piece of work.

One of the primary objects of this invention is to provide a simpleholding block for the thread cutting tool to be sharpened or shaped,having different angular faces on its sides which correspond exactly tothe angle of the faces and edges to be given to the thread cutting toolheld by the block, whereby by turning the block in proper sequence onits different faces, the cutter will be held at the exact desired anglerelative to the grinding wheel.

Another salient object of the invention is to provide a grinding blockfor association with a magnetic chuck of a grinding machine,embodying'like angular faces on its opposite "sides corresponding to theangle of the side faces of the thread cutter, an angular face on itsrear end corresponding to the desired angle of the leading edge of acutter, and fiat, horizontal faces n its top and bottom corresponding tothe top edge of the tool. I v

invention is the provision of a tumbler rotatably carried by the blockin which the cutter is clamped with means for settin and holding thetumbler and Q the tool at the exact desired angle corresponding to thehelix angle of the thread to be formed by the tool.

, With these and other objects in view, the invention consists in thenovel construction, arrangement and formation of parts, as will behereinafter more specifically described, claimed and illustrated in theaccompanying drawing, in whichdrawing:

Figure 1 is a side elevational view of my novel grinding block with athread cutter clamped therein and with the block laid on one of its sideangular faces for the grinding of one side face of the tool. V

Figure 2 is a central, longitudinal, sectional view through the blockshowing the block laid on its bottom flat horizontal face.

Figure 3 is a front elevational view of the block with the tool thereinand shown in section, the section bein taken on the line 3-3 of Figure2, looking in the direction of the arrows.

Figure 4 is a transverse sectional view through the block and tool, thesection being taken on the line 4-4 of Figure 2, looking in thedirection of the arrows, illustrating the means for clamping the tool inthe tumbler.

2 Figure 5 is a transverse sectional view through the block and tooltaken on the line 5-5 of Figure 2, looking in the direction of thearrows,

illustrating the means employed for clamping the tumbler to the block.

Figure 6 is a transverse, sectional view through the block, taken on theline 6-6 of Figure 2, lookin in the direction of the arrows.

Referring to the drawing in detail, wherein similar reference charactersdesignate corresponding parts throughout the several views, the letter Bgenerally indicating my novel grinding block for a thread cutting toolT.

The thread cutting tool T is of the type commonly employed for cuttingthreads in a piece of stock, and hence includes the usual bit It! andcutting head I I. The cutting head H, includes the usual side angularfaces l2 leading toward the angular front edge [3.

The grinding block B is formed from a single solid piece of metal havinthe properties of being attracted to and held by magnetic chuck C. Thegrinding block B has formed axially therein a cylindrical bore [4, whichopens out through the front end of the block. The front face of theblock can be provided with an annular rabbet l5 around the bore [4.

Rotatably mounted within the bore 14 is a tumbler IS. The forward end ofthe tumbler is provided with an annular flange H, which is snuglyreceived within the rabbet l5. The tumbler l6 and its flange l1 fitaccurately within the block, but is free for turning movement therein.The axial center of the tumbler is provided with a socket H! whichsnugly receives the bit ll] of the tool. Obviously, the cros sectionalconfiguration of the socket I8 corresponds to the cross sectionalconfiguration of the bit. Extending into the tumbler I6 is a set screwl9 and this set screw is employed for tightly clamping the bit of thetool in the tumbler. To permit turning of the tumbler in the block, theupper face of the block is provided with a transverse slot 20 and theset screw l9 moves in this slot during the turning of the tumbler.

The tumbler is also clamped tight in the block after the settingthereof, as will be later pointed out, and this clamp includes afriction shoe 2| received in a semi-circular groove 22 formed in thetumbler I6. Bearing against the shoe is a set screw 23, which isthreaded in the block. Obviously, by threading down on the set screw,the shoe can be brought into firm clamping engagement with the tumbler.

The front face of the block has formed thereon or associated therewith,a scale 24, and this scale is graduated for left hand and right handthreads. The tumbler is provided with an indicating arrow or line 25,for cooperation with the graduations.

The formation of the outer surface of the block is important and thesefaces correspond to the angularit of the faces of the tool to besharpened and shaped. The bottom and top faces 26 and 2'! of the blockare fiat and parallel to one another, and parallel to the gripping facesof the magnetic chuck C.

The side faces 28 and 29, adjacent to the rear end of the block anglerearwardly to the longitudinal axis of the block. The exact angle ofthese faces is carefully computed to correspond to the side face [2 ofthe cutting tool exactly. The rear face of the block 30 is angularlydisposed relative to the transverse axis of the block. The angle of theface 30 is carefully formed and corresponds exactly to the angle of thefront edge l3, Of the tool.

In the use of my block the tool bit it] is placed Within the socket l8and is firmly clamped therein by the set screw l9, as is commonly shownin Figure 2. The helix angle is computed and the tumbler IS with thetool inside is turned to the corresponding angle on the scale 24 forright or left hand threads, as the case may be. The set screw 23 is nowtightened to lock the tumbler in its set position. The tool T is thenready for grinding. The block B is then laid on the face 28, as shown inFigure 1, on the chuck C, in the correct position relative to thegrinding wheel (not shown), and the tool is ground on one side;

After this side is ground, the block is turned and tool gage. Ifnecessary, for some tools, the block is laid on its face 21 and theupperedge of the tool is ground.

From the foregoing description, it can be seen that I have provided anexceptionally simple block in which, after the tool is once set in theblock in the desired angle, the faces thereof can be accurately groundby the mere turning of the block on its different angular sides.

Obviously diiferent blocks can be provided for different characters ofthreads.

Various changes in details may be made without departing from the spiritor the scope of my invention, but what I claim as new is:

In a grinding block for threaded cutting tools adapted to be associatedwith a magnetic chuck, a solid body having different angular faces onits outer sides corresponding exactly to the angu lar faces and edges ofthe tool to be sharpened and a fiat front face, said block having anaxial bore opening out through the front face and a transverselyextending slot communicating with the bore opening out through a side ofthe block, the front face of the block having an annular rabbetsurrounding the bore, a tumbler mounted in said bore for receiving atool, an annular flange on the forward end of the tumbler received insaid rabbet and said flange having its 'outer face flush with the frontface, a set screw received in the slot threaded in the tumbler forclamping engagement with the tool in the bore, said setscrew beingmovable in the slot for turning the tumbler, means carried by the blockadjacent to the slot for clamping the tumbler and tool in a desiredset'position in the block, said block and tumbler having a cooperatingscale and indicator.

FRANK A. VAVRIN.

REFERENCES CITED The following references are of record in the file ofthis patent;

UNITED STATES PATENTS Number Name Date 727,355 Han-sen Ma 5, 19031,908,155 Jorgensen May 9, 1933 2,385,902 Wilson Oct 2; 1945

